Neutral thermospheric winds deduced above Millstone Hill, 1. Mathematical model, uncertainties, and representative results

Incoherent scatter radar measurements from Millstone Hill have been combined with mass spectrometer/incoherent scatter (MSIS) model neutral densities to derive exospheric temperatures and the neutral wind component at 300 km parallel to the magnetic field. These quantities have been used to determine the neutral horizontal pressure gradients and winds in a dynamical model of the thermosphere above the radar site. The model can be extended in latitude with further assumptions to find the vertical velocity via the continuity equation. The uncertainties involved in these neutral wind determinations are examined. Representative summer and winter results are presented and compared with results of calculations in which the pressure gradients were taken from the global Ogo 6 and MSIS models. Zonal velocities derived from the Millstone Hill results were found to be larger than those for the empirical models because the zonal pressure (diurnal temperature) gradients were much steeper over parts of the day.